With the advancement of information communication technologies, various wireless communication technologies have recently been developed. Among the wireless communication technologies, a wireless local area network (WLAN) is a technology whereby high-speed Internet access is possible in a wireless fashion in homes or businesses or in a region providing a specific service by using a portable terminal such as a personal digital assistant (PDA), a laptop computer, a portable multimedia player (PMP), etc.
It is assumed that WLAN communication conforming to the institute of electrical and electronics engineers (IEEE) 802.11 standard is achieved in a region called a basic service set (BSS). A BSS region may differ according to a propagation characteristic of a wireless medium, and thus has an ambiguous boundary. The BSS can be classified into two structures, i.e., an independent BSS (IBBS) and an infra-structured BSS. The former is to constitute a self-contained network and denotes a BSS in which an access to a distribution system (DS) is not allowed. The latter includes one or more access points (APs), DSs, etc., and generally denotes a BSS in which the APs are used in all communication processes including communication between stations (STAs).
As a special type of network, a mesh network is defined in the WLAN. The mesh network may be defined as a network which supports direct communication between a plurality of wireless devices having a relay function without via an AP. Functionally, a DS of the AP can be replaced with a multi-hop path between the plurality of wireless devices. According to the mesh network, any one of the wireless devices can establish a peer-to-peer wireless link (i.e., a peer link or a mesh link) with another neighboring wireless device. Since the peer link can operate as a multi-hop path, there is an advantage in that a wireless connection can be more flexibly established.
FIG. 1 shows an exemplary structure of a mesh network. The mesh network has a unique mesh identifier. The mesh identifier is a shortened term used to identify a group of mesh points (MPs) constituting the mesh network. There is no restriction on how to assign the mesh identifier.
Referring to FIG. 1, the mesh network includes one or a plurality of STAs 131, 132, 133, and 134 and one or more wireless devices, i.e., MPs 111, 121, 122, and 123. Among these MPs, the MPs indicated by the reference numerals 121 and 122 are connected to the STAs 131, 132, 133, and 134. Thus, each of the MPs 121 and 122 acts as an MAP defined as a MP which also functions as an AP. In addition, the MP indicated by the reference numeral 121 is an MP connected to an external network in a wired or wireless fashion, which is called a mesh portal.
Each of the STAs 131 to 134 is a non-AP station and is an arbitrary functional medium including a medium access control (MAC) and physical layer interface for a wireless medium, conforming to the IEEE 802.11 standard. In addition to the terminology of a wireless station, the STA may also be referred to as a wireless transmit/receive unit (WTRU), a user equipment (UE), a mobile station (MS), and a mobile subscriber unit, etc.
Each of the MPs 111, 121, 122, and 123 is a constitutional element of a wireless mesh network and is one of IEEE 802.11-based functional entities including the MAC and physical layer interface conforming to the IEEE 802.11 standard. Each of the MPs 111, 121, 122, and 123 is a wireless device supporting a mesh service. The mesh service includes various services for enabling direct communication between the MPs constituting the mesh network. Communication between two MPs (e.g., the MPs indicated by reference numbers 121 and 123) for providing the mesh service is achieved through a peer link or a mesh link which is a direct link established between the two MPs.
In addition to the aforementioned functions of the MPs, each of the MAPs 121 and 122 also functions as an AP for an associated STA having a connection established to the MAPs 121 and 122. In the infra-structured BBS, the AP relays a frame for the STA and performs various functions for BSS management. In addition to the terminology of an access point, the AP may also be referred to as a centralized controller, a base station (BS), a node-B, a site controller, etc.
Meanwhile, in the WLAN, a regulatory class is defined in association with a frequency bandwidth or the like. The regulatory class is an index into a set of values for radio equipment sets of rules. One regulatory class includes various regulatory requirements on communication in a specific frequency bandwidth. For example, the regulatory class may differ according to combinations of a channel starting frequency, a channel spacing, a channel set, a transmit power limit, an emission limits set, a behavior limits set, etc. Accordingly, the same regulatory class is required when an MP establishes a peer link with another MP for communication. In addition, the same channel has to be used in communication between a plurality of channel sets defined in the same regulatory class.